We have a lot of fun running mock attacks in class. In one scenario, the teacher will instruct a couple students to mock attack another student. This can be open hand, stick or practice knife. This can happen at virtually any moment. This make you very aware of perceived odd moving in class. Another scenario, would be when sparring/speed building with one student, another student just suddenly takes over, even from the flank. We don’t do this every class session, but often enough so folks are always slightly on guard. We typically leave new students out of this, but they see it and become aware of the possibility. Fun stuff!